A pop-up drain plug is typically characterized by a cap at one end to open and close the plug seat or entry opening of the drain pipe. The base at the other end of the plug is acted upon by actuator means which move the plug up and down in the drain pipe. When the plug is up, water is free to flow from the sink, tub or the like, beneath the raised cap of the plug, and through the entry opening into the drain pipe. The water then flows past the intermediate portion of the plug. This portion includes a guide whose radially outwardly directed fins slidably engage the drain pipe walls to guide the plug in its up and down movement. The intermediate portion also includes a stem located between the guide and the plug base. Typically the stem is of a lesser cross section than the guide because there is no need for the fins to extend all the way to the base to insure alignment of the plug with the drain pipe. Also, the fins normally do not extend above the drain entry opening, even in the uppermost position of the plug.
Under these circumstances, small articles such as contact lenses and jewelry items can accidentally be carried into the drain pipe with any water draining into the entry opening. The same is true of foreign substances such as hair, which can eventually clog the drain pipe.
There are surface strainers in the prior art which can be placed adjacent the plug seat or entry opening, flush with the adjacent sink or tub surface, but this cannot be done until the drain plug is removed. Then, when the sink is to be filled, the strainer must be removed and the plug inserted. Emptying the filled sink so that all foreign objects are caught in the strainer is even more challenging because the strainer must be immediately positioned after the plug is removed.
U.S. Pat. No. 1,203,530, entitled "Combination Drainer and Stopper", issued to W. R. Gessler on Oct. 31, 1916, show a surface strainer which can be left in the drain opening at all times. However, the strainer will not work with a pop-up type of drain plug. Each time such a pop-up plug is raised the guide fins on the plug would move up against the strainer and pop it out of the drain opening. Instead of a pop-up drain plug Gessler teaches a sink stopper which completely overlies the strainer. One feature of his strainer is that it is attached to a rod which slides through the center of the strainer A disk-like base on the lower end of the rod engages the underside of the strainer whenever the householder wants to remove the strainer for cleaning. Otherwise, the strainer normally remains in one position, and in no event does it move with the rod.
U.S. Pat. No. 4,380,834 entitled "Pop-Up Plunger", issued on Apr. 26, 1983 to F. E. Wentz, discloses a pop-up drain plug and integral strainer which do move together. The strainer is designed to entrap small articles moving toward the drain opening with the drain water. However, such entrapment occurs before such articles pass through the drain opening. This is done by an apertured sleeve attached to and extending downwardly from the cap of the plug. The sleeve rises with the plug cap and is at all times in the path of the drain water, regardless of the height of the raised plug above the drain opening. Water can pass into the sleeve but small articles cannot. The complete length of the strainer must be precisely dimensioned to closely fit against the drain pipe walls so that small articles cannot fall between the strainer and the drain pipe in any raised position of the plug. As Wentz points out, this necessitates tolerances of two and one half to ten thousandths of an inch between the strainer and the adjacent drain pipe surface, and he indicates it may be necessary "to bore out or ream out the interior of the waste drain pipe." If close tolerances are not observed small articles, and particularly a contact lens, could slip between the strainer and the drain pipe. Needless to say, the installation procedure mentioned would be time consuming and not within the skill of most householders.